Improvement in automatic telegraphs



T. A. EDISON.- AUTOMATIC TELEGRAPH.

Patented 0ct.2,1877.

RislsTANcE RECEIVER NR EMMNSYR rum, FNOTQLITHOGRAPHH, WASHINGTBN. D O

UNITED STATES PATENT OFFICE;

THOMAS A. EDISON, OF NEWVARK, NEW JERSEY, ASSIGNOR TO HIMSELF AXD GEORGEHARRINGTON, OF WASHINGTON, DISTRICT OF COLUMBL IMPR OVEM-ENT INAUTOMATIC TELEGRAPHS.

Specification forming part of Letters Patent No. 195,752, dated October2, 1877 application filed January 27, 1875.

To all whom 'it may concern:

Be it known that I, THOMAS A. EDISON, of Newark, in the county of Essexand State of New Jersey, have invented an Improvement in AutomaticTelegraphs, of which the following is a specification:

The object of this invention is to transmit, over telegraphic circuits,dashes the first part of each of which is formed by a stronger currentthan the last, so as to prevent the wire from being fully chargedstatically also, in arranging in the main line at the receivingstation acondenser formed of plates separated by air on] y.

The invention consists in the method of arranging the perforations andcontact stylus or rollers to send a strong current by putting on thewhole of the battery to form the first part of adash, and immediatelythereafter a second stylus closes the circuit through one of the holesintended for a dash, so as to preserve the continuity, but only to puton a portion of the battery.

Figure 1 shows the arrangement of perforations for the word That, and 2shows the arrangement of parts and connections.

The first stylus, a, passing into the first hole, closes the circuit,and puts the whole battery (1 upon the line. Just at the moment it isleaving this hole the middle stylus or pen 1) falls into the secondhole, preserving the continuity of the circuit, but putting on only halfof the battery. The third pen, 0, puts on the whole of the battery, andforms the dots.

It the ends of the stylus or pens are in line, one perioration will bein ad 'ance of the next to form the dash; but it the point of one stylusis farther in advance than the next, the perforations may be in hne witheach other transversely of the strip, and two styluses in place of threemight be similarly employed.

R is a branch to earth for the static discharge of the line. C is anordinary condenser,

shunted with a resistance, R the object of? which is to give a morepowerful compensationi should the air-condenser C prove insut'ticient ,5but generally the resistance 11 is made nil on, short-eircuited, so thatthe condenser C is dispensed with. The first portion of a signal! comingover the wire records itself on thel chemicallyinepared paper, and atthe samd time charges the condenser C. Now, when the signal ceases, thecondenser C discharges a contrary current, which balances that froni theline. i The reason of sending a weaker current to form the last portionof a dash is to prevent the wire from being charged higher with a dashthan a dot, thus preserving an evenness in the recorded dots and dasheswhich it is very hard to obtain on very long circuits. I use anair-condenser, C, so that it will dist charge instantly, which is notthe case witli oondensiiig-surt'aces separated with a non-com ductingmaterial, the phenomenon of absorp tion preventing their dischargingquickly and reducing the speed. I believe I am the first to discoverthat an air-condenser applied to a chemical telegraph will promoterapidity of operation at the rd ceiy'ing-instrument. 1

I claim as my invention 1. The air-condenser inserted in the line at thereceivingstation of a chemical telegraph, for the purposes set forth. 2.In a chemical tclegraph,the method specified of forming dashes bytransmitting, by means of perforated paper, a strong current followed bya weak current, substantially as Set forth. Signed by me this 19th dayof January, A. D. 1875. THOS. A. EDISON.

\Vitnesses i G120. '1. PINCKNEY,

CHAS. I-I. Smrn.

